Here follows a simple ’step-by-step’ guide to fitting Marmox Construction Boards with underfloor heating onto a concrete or screed floor. Marmox can also be used in a wall application but that is not covered here.
To fit Marmox with floor heating onto a concrete floor:
- Lay the boards
- Tape the joints
- Fit your floor heating
- Tile the floor
1. Lay the boards
Ensure the floor is level and dust free. New screed floors should be well cured prior to laying Marmox board.
The boards should be laid using a flexible tile adhesive. Apply the adhesive to the floor with a notched trowel. The Marmox boards should be thoroughly bedded ensuring that there are no voids under them. Butt them together with the joints offset in a brickwork type pattern. A waterproof joint can be made by running a bead of silicone sealant along the edge of the board and butting the adjacent board up to it.
2. Tape the joints
When the adhesive is dry, tape the board joints.
For a wet area either use a good quality waterproof compound or waterproof tape. For all other areas ordinary Marmox joint tape should be used.
3. Fit the floor heating
Now lay the floor heating in accordance with the manufacturers’ instructions.
4. Tile the floor
Follow the manufacturers’ instructions for covering the floor heating cables, usually with flexible tile adhesive or a latex screed. The tiles should be a minimum of 50mm x 50mm and fixed using a thin solid bed technique ensuring no voids remain under the tiles.
Once the tile bed has hardened sufficiently, the joints between the tiles can be grouted in the usual manner.
Movement Joints
Marmox Insulation Boards must not bridge movement joints in the sub-floor. The integrity of these joints must be maintained through the board/tile bed and should be sealed in the appropriate manner.
